It would be very unusual for a 19 y.o. to be having coronary problems. You say your chest feels tight when you lie down at night. I wonder if it isn t just chest wall pain from your workouts. You say you get short of breath when you run, and you develop a pain in your lower left chest then. I don t know how bad your shortness of breath is. You can simply be short of breath running, because you are overweight or out of shape. Chest pain of a heart attack or angina usually presents right in the middle of your chest as a pressure type pain, not off on the left side like you describe. I would be more concerned about a valvular heart defect, than coronary disease. Have you ever had a heart murmer? I d recommend you go and get a good physical. He should listen to your heart carefully for any murmur. He should get a chest xray and a resting EKG. If there is any question of a murmur, I would get an echocardiogram. The chest xray as well as the echo, together with the physical exam would make sure you got a normal size heart and no valve abnormalities. The other thing he might want to get is a treadmill EKG, to see if when you have those symptoms running, there is any change in the EKG to indicate ischemia. You didn t say what your weight was. If you are overweight, I would recommend walking, rather than running, at least until you take off some pounds.